Hydraulic hoisting mechanism



HYDRAULIC HOISTING MECHANISM Filed Dec. 1, 1945 2 Sheets-Sheet l INVENTOR Emerson Hall L f ,y H m B m m u 9 8 2 2 ml 9 F March 9, 1948.

E. HAIL 2,437,466

HYDRAULIC HOISTING MECHANISM Filed Dec. 1, 1945 2 Sheets-Sheet 2 INVENTOR. Fig 2 Emerson Hail GA M Aff'y Patented Mar. 9, 1948 ATENT OFFICE HYDRAULIC HOISTIN G MECHANISM Emerson Hail, Lafayette, Calif. Application December 1, 1945, Serial No. 632,264

2 Claims. 1

This invention relates to improvements in a hoisting mechanism, and has particular reference to means for raising and lowering the boom of a crane or other similar mechanism.

The principal object of this invention is to provide hydraulic means for raising and lowering the boom of a crane.

A further object of this invention is to eliminate the use of a second boom, drum and hoisting cable.

A further object is to prevent twisting of the hoisting cables and boom raising cables as the boom is rotated about on its turntable.

A further object is to provide simpler means of operation.

A further object is to provide means for controlling the speed of raising through either engine speed or amount of port opening in the hydraulic system.

A further object is to provide a device where e it is impossible for a boom to move beyond a predetermined distance, thus eliminating any possibility of a boom falling over backwards.

A further object is to prevent the possibility of too rapid raising or lowering of the boom or the dropping of the boom through the operator forgetting to engage the usual locking pawls used with the ordinary cable and drum arrangement.

Other objects and advantages will be apparent during the course of the following description.

In the accompanying drawings forming a part of this specification and in which like numerals are employed to designate like parts throughout the same,

Fig. 1 is a side elevation of a crane having my invention applied thereto.

Fig. 2 is an enlarged detailed cross-sectional view of the hydraulic cylinder and turntable arrangement, and

Fig. 3 is an enlarged detailed view of the oil transfer.

In the ordinary hoisting mechanism com monly called a crane it has been customary to provide either a stationary or movable base, upon which is mounted a turntable and to which is pivoted a boom, which may be rotated about a vertical axis, and also this boom may be raised and lowered about its pivotal connection to the turntable.

It has been customary to provide two drums, one of which actuates the hoisting cable, which is connected to the hoisting hook, which drum is manipulated through a series of clutches, brakes and locking pawls.

A similar arrangement is used for the purpose of raising and lowering the angular positioning of the boom.

As these two cables both pass upwardly through the turntable and as the drums are im movably positioned beneath the turntable it is obvious that as the boom rotates about the vertical axis of the turntable two cables must of necessity twist upon themselves, which twisting causes rapid wear of :the cables and it becomes diflicult for the operator to properly work the lines.

I have therefore perfected a hydraulic mechanism for raising and lowering of the boom, which eliminates the use of a boom-raising cable; also, simplifies the control .of the movement of the boom, and further eliminates any possibility of the boom moving either upwardly or downwardly beyond a given distance, and therefore the boom cannot possibly be pulled over backwards, as is now often the case, with resultant damage not only to the boom, but danger to the operator.

In the accompanying drawings wherein for the purpose of illustration is shown a preferred embodiment of my invention, the numeral 5 designates any type of support, here shown as a mobile tractor, upon which is mounted a turntable base 6, which in turn carries a turntable i, supported by a driving ring 8, to which it is secured by bolts 9.

This driving ring has a worm gear H which engages a driving worm l2.

The arrangement thus far described permits the crane to be rotated about a vertical axis.

A plate I4 is secured to the turntable 1 by securing bolts I6 and this plate has mounted thereon a pair of spaced standards I 3 and a pair of ears I5, to which the lower bifurcated end of the boom I1 is pivoted.

The construction thus far described may relate to any standard form of crane and has no part in my invention.

My invention consists in mounting between the standards l3 a hydraulic cylinder 18, which is pivoted as at l9, so as to move simultaneously with the varying angle of the boom as the same is raised or lowered.

This cylinder has a piston 2| which is connected through a piston rod 22 to a yoke 23, having a sheave 24, about which sheave the middle part of a cable 26 passes. The opposite ends of this cable are attached as at 21 to the boom l1.

In order to move the piston 2| in the cylinder I provide a suitable hydraulic supply which is 3 conducted through the pipe 28 to a ring 29 carried by bracelets 30 on the turntable base 6.

This ring 29 has a groove 3| around its inner periphery, which communicates with the pipe 28. A similar ring 32 is positioned within the ring 29 and has a groove 33 which coincides with the groove 3|. This ring 32 is secured to the plate M by bolts 34.

Packing rings are shown at 36 to prevent leakage between the two rings.

A pipe 3'. communicates with the groove 33 and has its opposite end connected through a check valve 38 to the interior of the cylinder IS.

A bleeder is shown at 39 for the opposite end of the cylinder, and an oil trap is shown at 4| to take care of any leakage past the piston 2|.

The result of this construction is that when the parts are arranged as shown in the figures and it is desirous of raising the boom, for example, the operator merely opens a valve, which permits oil pressure to enter the pipe 28, passes into the groove 3| of the ring 29, thence to the groove 33 of the ring 32, from which point it will pass into the pipe 31 and upwardly through the check-valve 38 and into the cylinder, exerting pressure against the piston 2| and forcing the same toward the bottom of the cylinder. Thus, tension will be exerted on the cables 26 and the boom will be raised about its pivoted points The operator may now rotate the entire turntable throughout any desired degree of arc and then manipulate the load line, and the boom will stay in its elevated position.

Should the operator forget to shut oif the pressure when the piston reaches the end of its stroke it cannot go any further, and the oil pressure will then be bypassed back to the pump and storage tank in the usual manner.

Also, as the boom is lowered, should the operator forget to shut the releasing valve, then when the piston 25 reaches the end of its stroke going in the lowering direction the boom cannot drop any further and no damage will be done.

Should the pipe 31 break the check valve 38 will actuate to prevent a rapid flow of oil from the cylinder and will entirely close off the passage of oil, so that the boom will remain in fixed position. This check-valve only actuates under excessive discharge of oil through the line.

It will thus be apparent that my device performs all of the objects above set forth.

It is to be understood that the form of my invention herewith shown and described is to be taken as a preferred example of the same and that various changes relative to the material, size, shape and arrangement of parts may be resorted to without departing from the spirit of the invention or the scope of the subjoined claims.

Having thus described my invention, I claim:

1. In a hoisting mechanism, the combination with a rotatable turntable, rotatable about a vertical axis, a boom pivotally mounted on said turntable, a pair of spaced supports mounted on said turntable, the upper ends of said supports being offset from the vertical axis of said turntable and at a point above the pivotal axis of said boom, a cylinder horizontally pivoted between said supports, a piston movable in said cylinder, a rod connecting said piston, and a cable extending from said rod to said boom at a point substantially midway of its length, whereby actuation of said piston in said cylinder will move said boom about its pivot. 2. In a hoisting mechanism, the combination with a rotatable'turntable, rotatable about a vertical axis, a boom pivotally mounted on said turntable, a pair of spaced supports mounted on said turntable, the upper ends of said supports being offset from the vertical axis of said turntable and at a point above the pivotal axis of said boom, a cylinder horizontally pivoted between said supports, a piston movable in said cylinder, a rod connecting said piston, a cable extending from said rod to said boom at a point substantially midway of its length, whereby actuation of said piston in said cylinder will move said boom about its pivot, a pair of abutting rings mounted in said turntable, each of said rings having an abutting grooved means for conducting fiuid to one of said rings, and means for conducting fluid from the other of said rings to one end of said cylinder.

EMERSON HAIL.

REFERENCES CITED The following references are of record in the 

